A belt continuously variable transmission changes groove widths of pulleys by hydraulic pressure to steplessly change a speed ratio. For such configuration, if the hydraulic pressure supplied to pulley vibrates for any cause, the speed ratio changes to cause driving force change, thus a vehicle body vibrates. The vibration of the hydraulic pressure often occurs caused by, for example, an oil pump structure, an oil passage structure, and valve characteristics.
In this respect, JP 2005- 121127A discloses a technique that an accumulator is coupled to an oil passage from an oil pump up to pulleys to absorb hydraulic pressure by the accumulator.